920每日博客

今天对Javaweb的用户登录类型进行判断的实现，以前使用过，但是没有发出来，今天讲一下我的想法，

首先是Java读取MySQL的：

public String login(int Id, String Password) throws SQLException {
    String sql = "select * from user ";
    Connection conn = Dbutil.getConnection();
    Statement st = null;
    List<UserBean> list = new ArrayList<>();
    UserBean bean = null;
    ResultSet rs = null;
    try {
        st = conn.createStatement();
        st.executeQuery(sql);
        rs = st.executeQuery(sql);
        while (rs.next()) {
            int id = rs.getInt("id");
            String pass = rs.getString("password");
            String type = rs.getString("type");
            bean = new UserBean(id, pass, type);
            list.add(bean);
        }
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        Dbutil.close(st, conn);
    }
    for(int i=0;i<list.size();i++){
        if(list.get(i).getId()==Id&&list.get(i).getPass().equals(Password)){
            return list.get(i).getType();
        }
    }
    return "登录错误";
}
这样的写法不是很好，不过想法就是返回这个用户用户类型，如果密码输入错误或者没有这个id的用户就返回一个登录错误的字符串，然后是在servlet进行判断：

public void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, SQLException, SQLException {
    request.setCharacterEncoding("utf-8");
    response.setContentType("text/html;charset=UTF-8");
    String id=request.getParameter("id");
    String password=request.getParameter("password");
    String res=dao.login(Integer.parseInt(id),password);
    System.out.println(res+"RESSS");
    if(res.equals("登录错误")){
        PrintWriter out = response.getWriter();
        out.print("<script>alert('登录失败!');window.location.href='Login.html'</script>");
    }
    else if(res.equals("用户")){

        HttpSession session = request.getSession();
        session.setAttribute("myid", id);
        request.getRequestDispatcher("User.html").forward(request, response);
        System.out.println(session.getAttribute("myid")+"session");
    }
    else if(res.equals("管理员")){

        HttpSession session = request.getSession();
        session.setAttribute("myid", id);
        request.getRequestDispatcher("Manager.html").forward(request, response);
    }
    
}
这里就是获得前台的登录时候的账号密码，然后根据读取数据库的用户类型返回的字符串进行判断，以此来跳转不同的用户界面